1. Field of the Invention
The present invention relates to a differential apparatus for an automotive vehicle.
2. Description of the Related Art
A differential apparatus 201 as shown in FIG. 1 is disclosed in Japanese Published Unexamined (Kokai) Application No. 2-38733. In this differential apparatus 201, a plurality of pairs of pinion gears 211 and 213 are accommodated in a plurality of accommodating holes 205 and 207 of a differential casing 203, respectively. The pinion gears 211 are in mesh with the pinion gears 213. Further, one side gear 217 is in mesh with the pinion gears 211, and the other side gear 219 is in mesh with the pinion gears 213, respectively. In the construction as described above, when differential motion is generated between two vehicle wheels linked with the two side gears 217 and 219, respectively, since the two pinion gears 211 and 213 are rotated under the condition that two tooth crest surfaces of the pinion gears 211 and 213 are brought into sliding contact with the inner wall surfaces of the accommodating holes 205 and 207 respectively, it is possible to generate a differential limiting force due to the frictional resistance generated at the sliding surfaces between both, respectively.
In the conventional differential gear, however, since a large frictional forces is generated between the tooth crest surfaces of the teeth of the pinion gears 211 and 213 and the inner wall surfaces of the accommodating hole 205 and 207 respectively, in case of insufficient lubrication, there exists a problem in that the differential limiting characteristics are not stable because of wear, gall, seizure, abnormal noise, etc. produced at the respective sliding surfaces between the pinion gears and the inner walls of the accommodating holes.